Conventionally, an optical pick-up device is used for recording and/or reproducing of information onto/from an optical information storage medium such as an optical disk. The optical pick-up device carries out recording and/or reproduction of information by, for example, (i) converging with an objective lens a light beam, which is emitted from a laser source, so that a recording surface or a reproducing surface of the optical disk is irradiated with the light beam, and (ii) detecting light reflected from the recording surface or the reproducing surface.
At the recording and/or the reproduction of information, the objective lens may collide with an optical disk due to a warpage of an optical disk or a defect in an optical pick-up device. As a mechanism for preventing the collision, a protective member is known.
Moreover, it is well known that a protective cover (actuator cover) in the vicinity of a lens holder for the purpose of (i) protect a mechanism including a lens holder and a lens driving section (both of which is included in an actuator unit) and (ii) prevent the mechanism from being contaminated.
With reference to FIGS. 9 through 11, an arrangement of a conventional optical pick-up device is explained below. A slim combo pick-up device is assumed as the conventional optical pick-up device. The slim combo pick-up device includes a DVD laser light source unit 140 and a CD laser light source unit 150.
FIG. 9 is a diagram illustrating an arrangement of the conventional optical pick-up device. FIG. 9 shows one example of each of (i) an arrangement of a typical slim combo pick-up device that records/reproduces information onto/from an optical disk 160 (Refer to FIG. 10) that is an optical storage medium, (ii) a housing 110, (iii) an actuator unit 120, and (iv) a protective cover 130 for protecting the actuator unit 120. (a) of FIG. 9 is a plan view of the optical pick-up device, and (b) of FIG. 9 is a back view thereof. FIG. 10 is a cross sectional view taken along F-F′ of the actuator unit 120 in (a) of FIG. 9, and illustrates an arrangement that includes the optical disk 160, an objective lens 121, a lens protector 127, and a protective cover 130 when the arrangement in (a) of FIG. 9 is viewed in a focus direction. FIG. 11 is a diagram illustrating the actuator unit 120 in details. (a) of FIG. 11 is a plan view of the actuator unit 120 and (b) of FIG. 11 is a side view illustrating a side surface of the actuator unit 120 in (a) of FIG. 11.
In the slim combo pick-up device, a laser beam emitted from each of the laser light source units 140 and 150 passes through a special optical component. Then, a raising mirror 145 changes an optical axis direction of the laser beam according to a direction in which a recording surface of the optical disk 160 is irradiated with the laser beam. Subsequently, the laser beam is converged onto the optical disk 160 with the objective lens 121 so that reading/writing of disk information is carried out.
Next, an actuator unit 120 of the optical pick-up device is explained with reference to FIGS. 10 and 11.
A magnetic circuit is formed with a tracking coil magnet (not shown), as a mechanism for shifting in a radial direction a lens holder 122 which holds the objective lens 121. Moreover, another magnetic circuit is formed with a focusing coil magnet (not shown), as a mechanism for shifting the lens holder 122 in a focus direction.
The lens holder 122 is suspended by thin wires 125 extended from the actuator base 126, and included in the actuator unit 120. The actuator unit 120 is fixed in the housing 110 in FIG. 9.
For example, Patent Document 1 discloses a proposal for improving the problem of a collision between the protective cover 130 and the optical disk 160 which problem occurs when a recent thin-model notebook computer writes information onto the optical disk 160, particularly a commercially available optical disk having a lot of run out.
In the arrangement of Patent Document 1, the protective cover 130, which is a component separate from the housing 110, is attached to the actuator unit 120, and a protrusion is provided on a surface of the protective cover 130 which surface faces the optical disk 160. This arrangement requires to maintain a high component accuracy. Moreover, additional material cost and operation cost occur for the attachment of the separate component. Furthermore, a conventional cover is often made of thin sheet metal or thin molded resin, which, however, causes the problem of insufficient strength of the conventional cover.
Patent Document 2 discloses a conventional art in which a protective cover 130, which is separately provided in the actuator unit 120, has the function of protecting the mechanism in the actuator unit 120 and the function of protecting the mechanism in the actuator unit 120 from dust.
Furthermore, Patent Document 3 discloses an arrangement in which a surface of a protective cover 130 which surface faces an optical disk 160 is curved. The curved surface makes it difficult that turbulent airflow flows into a hole, and thus keeps dust floating in the air off the hole.
However, the conventional optical pick-up device and the conventional optical recording/reproducing apparatus have the following problem. Namely, it is difficult to provide an optical pick-up device and an optical recording/reproducing apparatus both of which can realize (i) a stable component accuracy, (ii) improvement in productivity, and (iii) low cost, without damaging an optical disk.
More specifically, the following problem occurs.
A conventional mechanism for preventing the collision between the optical disk 160 and the objective lens 121 in the above-mentioned Patent Documents 1 through 3 is realized by providing the protective cover 130 or the protruding lens protector 127 in vicinity of the objective lens 121 of the lens holder 122.
The lens protector 127 can function as a mechanism for preventing a collision between the optical disk 160 and the objective lens 121 when the objective lens 121 is driven in a focus direction.
However, the lens protector 127 does not function as a protector of the actuator unit 120, when the optical pick-up device is not in operation or when the optical pick-up device is being produced or assembled.
Accordingly, in order to protect the actuator unit 120 during the aforesaid occasions, the protective cover 130 needs to be attached to the housing 110.
Patent Document 2 discloses a method of engaging the housing 110 with the protective cover 130 so that a positioning accuracy of the housing 110 and the protective cover 130 is improved. In each case, attachment of the separate protective cover 130 is necessary for obtaining the housing 110 provided with the protective cover 130. This leads to the problems of increase in component cost, increase in operation cost for the attachment, unstable component accuracy, and insufficient component strength.    [Patent Document 1] Japanese Unexamined Patent Publication No. 251246/2005 (Tokukai 2005-251246 (published on Sep. 15, 2005))    [Patent Document 2] Japanese Unexamined Utility Model Publication No. 142720/1987 (Jitsukaishou 62-142720 (published on Sep. 9, 1987))    [Patent Document 3] Japanese Unexamined Utility Model Publication No. 28531/1991 (Jitsukaihei 3-28531 (published on Mar. 22, 1991))